Methods for Air Leak Detection

[whoosh929]

I am looking for suggestions on how to detect locations of air leakage within a pressurized system. Unfortunately, I must be vague in the description of the system.

Essentially, my system contains a reservoir at vacuum pressure (approximately - 35 kPa). This reservoir is connected to a bank of tiny valves (valves are approximately 10 mm apart), which I suspect at least some may be leaking into atmosphere (when monitoring reservoir pressure, the pressure slowly increases). The requirement in our design is that this reservoir cannot leak more than 0.15 kPa/min.

What are some recommended methods to determine where leak is occurring?

Thanks in advance for your help.

 

[monkeydog]

Isolate and leak check

 

[georgeverghese]

A probable location for inward leaks is the stem packing on these valves - did you specify these valves to be good for vacuum service ? - they would have extended packing boxes if I'm not mistaken.

If you could hold a tracer gas ( helium if you can afford it) lance near the packing on each of these stem packings, that might help you locate the leak, but I doubt this will work well if these valves are only 10mm apart. The other way would to replace all valves, excepting the one being tested, with gasketed blind plates.